Heat sink



FIG. 1 is a perspective view of a heat sink showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is second perspective view thereof;

FIG. 9 is third perspective view thereof; and,

FIG. 10 is a perspective view showing the heat sink in use.

The broken lines in the drawings illustrate portions of the heat sink that form no part of the claimed design. 

CLAIM The ornamental design for a heat sink, as shown and described. 